Tank with internal fail-safe valve

ABSTRACT

An improved enclosed storage tank, for a liquid product, having a bottom opening communicating with a discharge pipe, and a fixed-position roof, comprising a fail-safe apparatus for closing the bottom opening internally of the tank, said apparatus including the valve means inside of the tank, the valve means having a valve seat around the bottom opening and a valve closure adapted to span the bottom opening and contact the valve seat in closing the opening, and suspending means extending from the valve closure to a control means, said control means being capable when activated to raise and hold the suspending means in raised position with the valve closure above the valve seat and the valve thus open, and when deactivated to permit the suspending means to drop and the valve closure to automatically contact the valve seat and close the bottom opening.

Brogren Aug. 13, 1974 TANK WITH INTERNAL FAIL-SAFE VALVE 3,610,571 10/1971 c1566 251/144 x [75] Inventor: Erik E. Brogren, Wheaton, lll.

Primary Examiner-Robert G. Nilson [73] Asslgnee: Chlcago Budge & Iron Company Attorney, Agent, or Firm-Merriam, Marshall, Shapiro Oak Brook, 11]. & K1056 [22] Filed: Sept. 7, 1972 21 Appl. No.: 286,984 ABSTRACT An improved enclosed storage tank, for a liquid prod- 521 U.S. c1 l37/630.15, 251/62, 251/144, her, having a bottom p g communicating with a 251/294 discharge pipe, and a fixed-position roof, comprising a [51] Int. Cl. Fl6k 31/16 fail-Safe apparatus for Closing the bottom Opening 158 Field of Search 251/144, 294; l37/630.l5, temaliy 9f the tank, said apparatus including the valve 37/ 30 19; 4 2 30 52 7 R means inside of the tank, the valve means having a valve seat around the bottom opening and a valve clo- [5 References Cited sure adapted to span the bottom opening and contact I UNITED STATES PATENTS the valve seat in closing the opening, and suspending 380 I53 3/1888 weeden 4/52 means extending from the valve closure to a control 1 2lO'330 12/1916 Km" 4/30 means, said control means belng capable when acti- 18811807 10/1932 Maur e r iixil IIIIII 2 5 i/294 x il to false and hold the suspending means in raised 23415999 2/1947 Hooper 251/294 X pos1t1on w1th the valve closure above the valve seat 2,549,689 4/1951 Jurs I 251/144 X and the valve thus open, and when deactivated to per- 2,795,237 6/1957 Corbin, Jr. 4/67 R mit the suspending means to drop and the valve clo- 3,l02,555 9/!963 Botkin l37/630.l5 sure to automatically contact the valve seat and close 3,37l,l43 2/l963 Wynne l37/630.l5 X the bottom pening, 3,447,777 6/l969 Carlson 251/294 X 3,555,572 l/l97l Thomas 4/52 X 9 Claims, 7 Drawing Figures PAnzmzuwm m I 3.8289819 SHEET 1 [IF 3 SHEET 2 OF 3 This invention relates to fail-safe apparatus. More particularly, this invention is concerned with a fail-safe valve apparatus suitable for use in storage tanks which hold liquids, and particularly flammable liquids including cryogenic liquid materials.

Various kinds of liquid materials are stored in large tanks. Many of the stored liquids are highly flammable materials, including those which are liquid under ambient conditions as well as those which are liquidified gases, such as liquefied natural gas. Various pipes or conduits communicate with each storage tank so that the tank can be filled with, and emptied of, a liquid product. Control valves are placed in such pipes at strategic places for necessary liquid flow control. Such control valves, however, are placed exterior of the tank. If the valve or pipes should fail for any reason, such as through an explosion, fire or sabotage, the entire tank contents could be emptied before the damage is repaired. Not only would a great amount of liquid product be lost if this occurred, but it would also present an extremely dangerous situation in the case of an escaped liquid flammable product. There is, accordingly, a'need for a control system or apparatus which will prevent the liquid content of a tank from emptying if there is a failure of an exterior pipe or valve in liquid communication with the tank interior.

There is provided according to the subject invention a fail-safe valve apparatus positioned largely inside of a storage tank for a liquid product to rapidly close off a bottom opening in the tank through which a liquid product could otherwise drain from the tank. By positioning the valve apparatus inside of the tank, flow of liquid product from the tank is completely stopped in the event this is necessary or desirable for any reason at all, such as if there is a failure in an exterior pipe or valve in communication with the tank bottom opening.

The fail-safe apparatus of the subject invention for internally closing a bottom opening of a tank includes a valve means inside of the tank. The valve means has a valve seat around the bottom opening and a valve closure adapted to span the bottom opening in the tank and to contact the valve seat in closing the opening. Suspending means extend from the valve closure to a control means, advisably located above the maximum liquid level capacity of the tank. The control means is capable when activated to raise and hold the suspending means in raised position with the'valve closure raised above the valve seat with the valve thus open, and when deactivated to permit the suspending means to descend or drop and the valve closure to automatically move into contact with the valve seat and thereby close the bottom opening.

To aid in positioning the valve closure on the valve seat, the valve is advisably provided with telescoping guide means which permits vertical displacement of the valve closure relative to the valve seat, but which permits only slight horizontal movement of the valve closure relative to the valve seat. The slight horizontal movement is due to clearance provided between the telescoping parts to prevent binding and to facilitate proper seating of the valve closure on the valve seat. The telescoping guide means can include a vertical tube on the valve closure in which a rod, fastened to a supporting means at or on the tank bottom, can slide.

The valve apparatus is furthermore advisably provided with an integral pressure-equalizing valve so that subsequent repositioning of the main fail-safe valve in open position can be achieved readily even though the tank has a high liquid head which applies a substantial pressure on the main valve. The pressure equalizing valve comprises an orifice in the first or main valve closure and a second valve closure capable of sealing the orifice. A connecting member extends from the second valve closure to an eccentric arm in the suspending means connecting the first valve closure to the control means. When a lifting force is applied to the suspending means by the control means, the eccentric arm first causes the connecting member to lift the second valve closure from sealing position about and over the orifice and to then lift the first or main valve closure from sealing contact with the valve seat. By first opening the pressure equalizing valve, liquid is permitted to flow from the tank into the pipe with which the tank bottom opening communicates. The flow of liquid through the pressure-equalizing valve soon causes the liquid pressure on each side of the first or main valve closure to become substantially equal, thereby permitting ready lifting of the first or main valve closure from the valve seat on which it is in sealing contact when the valve is closed.

Although the control means can be activated by hydraulic pressure or employ an electrical drive, it is more advisable to employ a control means which is pneumatically operable.

The invention will now be described further in conjunction with the attached drawings, in which:

FIG. I is a vertical view, partially in section, through a storage tank containing one embodiment of the failsafe valve apparatus of this invention installed therein;

FIG. 2 is an elevational view, partially in section, showing the valve apparatus of FIG. 1 in greater detail;

FIG. 3 is a partial vertical sectional view of means to accommodate expansion and contraction induced by temperature change on the valve lifting mechanism;

FIG. 4 is a plan view, partially in section, taken along the line 4-4 of FIG. 2;

FIG. 5 is an elevational view, partially in section, of another embodiment of the invention in which a pressure equalizing valve is provided in the main fail-safe valve;

FIG. 6 is an enlarged elevational view, partially in section, of the pressure equalizing valve shown in FIG. 5; and

FIG. 7 is a plan view partially in section taken along the line 77 of FIG. 6.

So far as is practical, the same elements or parts which appear in the different views of the drawings will be identified by the same numbers.

With reference to FIG. 1, storage tank 10 has a flat metal external bottom 11 and a vertical circular cylindrical external metal wall 12 on which domed roof 13 of metal plate is supported. Flat inner metal bottom 14 rests on load bearing insulation 15. Vertical circular cylindrical inner metal wall 16 is joined to the inner bottom 14. Insulation 17 is positioned between outer wall 12 and inner wall 16. Ceiling 18 is suspended by rods 19 from domed roof l3. Insulation 20 is supported on the upper surface of suspended ceiling 18 to thereby completely insulate the space surrounded by inner bottom 14, inner wall 16 and suspended ceiling 18.

Liquid is fed to tank by conduit 21. Vapor which forms in the tank beneath suspended ceiling 18 is removed through conduit 22, which directs the vapor to the space above suspended ceiling l8. Conduit 23 in roof 13 is used to remove vapor from the space above suspended ceiling l8 and below domed roof 13. During discharge of liquid from the tank, vapor or some other suitable gas is permitted to enter the tank by conduits 23 and 22 to prevent the formation of a substantially lower pressure inside the tank, which could lead to its collapse.

The bottom of tank 10 is provided with discharge pipe 24 for removing liquid product from the tank. The end of pipe 24 is joined to the inner bottom 14 and communicates with opening 25 therein. As shown in FIGS. 1 and 2, valve seat 26 comprising a circular plate having a central hole 27 (FIG. 4) is joined to inner tank bottom 14, such as by welding. Vertically positioned tube 28 is centrally located in hole 27 and it is held in place by vanes 29, located spider-like in hole 27. The vanes 29 also function as vortex breakers when liquid flows through opening 27 to discharge pipe 24.

Valve closure 30 is a thick circular metal plate provided with a seal or gasket 31, advisably made of polytetrafluoroethylene, positioned in a groove on the bottom face of the plate. Tube 32 is joined to closure plate 30 and extend upwardly therefrom for a sufficient distance to readily accommodate the entire length of tube 28, which fits inside thereof in a loose, slidable, telescoping arrangement. Metal tab 33 is joined to the closed top of tube 32. Extending upwardly from tab 33 is chain 34, of stainless steel or other suitable material, which is joined at its upper end to the lower end of rod 35. Rod 35 extends upwardly through collar 36 positioned in suspended ceiling 18.

The upper end of rod 35 is joined to bracket 80 by thread and nut means. Bracket 80 comprises a bottom plate 37 and an upper plate 38 held in spaced-apart relationship to each other by vertical legs 39 and 40. The threaded upper end of rod 35 is fixed to plate 37 by nuts 42 and 43 on each side of the plate.

Tubular vertically positioned member 41 is welded at its lower end to domed outer roof l3. Flange 42 is located on the upper end of tubular member 41. An opening in domed roof l3 permits bracket 80 to move in vertical displacement into the space beneath domed roof 13 as well as in tubular member 41 to the extent required for needed actuation of rod 35. Cylinder 44 is closed by plate 45 at its upper end and by plate 46 at its lower end. The peripheral portion of plate 46 rests on flange 42 and is tightly secured thereto by means of bolts 47. Piston 48 is positioned to slide vertically in cylinder 44. Connecting rod 49 is joined to the bottom of piston 48 and to bracket 80. The lower end of connecting rod 49 extends slidably through a hole in upper plate 38 in bracket 80. A plurality of Belleville spring washers 50 are positioned on the lower end of connecting rod 49 beneath plate 38 and are held in position by castellated nut 51 threaded on the lower end portion 52 of connecting rod 49. The Belleville spring washers 50 function as a means for adjusting the operating length of connecting rod 49 relative to rod 35 and chain 34 so as to accommodate any contraction thereof which may be caused by low temperatures to which rod 35 and which is illustrated by FIGS. 1 to 4, has the valve closure 30 positioned above valve seat 26 in normal operation of the tank. The valve closure is maintained in raised or open position by air or some other gas being fed under pressure by line 55 to cylinder 44. The gas pressure keeps piston 48 in raised position and it in turn lifts valve closure 30 by means of connecting rod 49, bracket 80, rod 35, chain 34 and tubular member 32. At such time as it becomes necessary to close the failsafe valve means, the gas pressure in cylinder 44 beneath piston 48 need only be lowered by reducing the gas pressure therein by opening a suitable relief valve means (not shown) in line 55. This can be effected manually or by automatic means. Upon reduction of the gas pressure, such as to atmospheric pressure, air or some other gas is advisably permitted to enter by line 56 into the space in cylinder 44 above piston 48. This results in a balance of pressure on each side of piston 48. The weight of the fail-safe valve closure 30 plus the weight of the suspending chain and rods results in instant dropping of valve closure 30 into sealing position on valve seat 26 as shown in FIG. 1. An additional closing force can be provided by a compression spring located in cylinder 44 and above piston 48.

The piston 48-cylinder 44 structure employed in the apparatus described with reference to FIGS. 1 and 2 is intended to be representative of the structure and operation of commercially available devices suitable for the described purpose. Such devices are often referred to commercially as actuators or operators. They normally operate by means of a compressed gas such as air. However, it is also within the scope of the invention to use a pressurized hydraulic liquid to operate the actuator. Electric means such as a spring loaded solenoid or linear actuator are also suitable operators.

To release the fail-safe valve closure 30 from sealing position, pressurized air or other gas is fed by line 55 into cylinder 44. The upward force thereby provided against piston 48 raises connecting rod 49, bracket 36, rod 35, chain 34 and tube 32 to thereby lift valve closure 30 from sealing engagement with valve seat 26. Because of the high pressure which is exerted on valve closure 30 when a high liquid head is in the storage tank 10, a considerable pressure must be exerted on piston 48 to raise the valve closure 30 from sealing position. Therefore, the air or gas fed by line 55 must be under a substantial pressure. Since the air or gas pressure readily available at a storage tank site might be lower than necessary to actuate the mechanism and release the fail-safe valve from sealing engagement, it is sometimes advisable to utilize a pressure equalizing valve in conjunction with the fail-safe valve apparatus to avoid any need to use an extra high pressure air or gas line to achieve the desired actuation for opening valve closure 30.

FIGS. 5 to 7 illustrate another embodiment of the invention in which a pressure equalizing valve is provided in conjunction with the main fail-safe valve means described with reference to FIGS. 1 to 4. Because many of the elements or parts employed in the second embodiment of the invention are the same as those described with reference to the first embodiment of the invention illustrated by FIGS. 1 to 4, the same numbers for the identical or common parts will be employed in FIGS. 5 to 7 and those parts will not be further described.

With reference to FIG. 5, valve closure 30A has a hole 60 extending therethrough. Ring 61 is centrally located in the upper part of a hole 60 and is held in fixed position therein by means of vertically positioned vanes 62 (FIG. 7) spaced apart from one another in a spider-like arrangement.

Valve closure 63 comprises a circular plate of such size as to cover or span the area of hole 60. Gasket 64 is located in a circular groove positioned in the bottom face of valve closure 63. When in closed position, valve closure 63 is lowered so that gasket 64 contacts the upper surface of main valve closure 30A.

The upper end of rod 65 is threaded into pressure equalizing valve closure 63. Rod 65 extends downwardly through a hole in ring 61. Belleville washers 66 are positioned on rod 65 beneath ring 61 and they are held in place by castellated nut 67 screwed on the end 68 of rod 65. Pin 59 (FIG. 6) through the end of rod 65 keeps nut 67 from unscrewing. A sufficient number of Belleville washers 66 are placed on the end of rod 65 to aid in keeping valve closure 63 in closed or sealing position. The Belleville washers function as a spring member to provide a tensile force on rod 65 to pull valve closure 63 into sealing position over hole 60.

Tab 69 is located on the top of valve closure 63. Rods 70 and 71 are joined to turnbuckle 72. The lower end of rod 70 is joined to tab 69 by a pin 73. Similarly, the upper end of rod 71 is joined by pin 74 to eccentric arm or cam 75. Pin 76 joins the eccentric arm 75 to tab 33 on the closed-upper end of tubular member 32. Chain 34 is also joined to eccentric arm 75.

As shown in FIG. 5, both valve closure 30A and valve closure 63 are in raised or open position when the failsafe valve mechanism is fully open. When in the fully closed position, valve closure 30A is seated on valve seat 26 and valve closure 63 of the pressure equalizing valve is in sealing position on the top surface of valve closure 30A over hole 60. Because of the eccentric arm or cam mechanism 75, as soon as tension is applied to chain 34, an upward force is conveyed by rods 70 and it 71 to valve closure 63 to preferentially lift it from sea]- ing position over hole 60 before valve closure 30A can be lifted from sealing position on valve seat 26. As soon as valve closure 63 is unseated and raised, the liquid contents in the tank begins to flow through hole 60 into discharge pipe or line 24. Once the pressure beneath valve closure 30A has been substantially reduced, or has been brought to a pressure about equal to the pressure on the upper side of valve closure 30A, a low gas pressure in cylinder 44 acting on piston 48 will cause valve closure 30A to be lifted readily even with a high liquid head in the tank.

The simplicity of construction and operation of the fail-safe valve apparatus of this invention are advantages not found in other devices. It can be used in a wide variety of insulated or noninsulated tanks and vessels used for storing both flammabe and nonflammable liquids at ambient, elevated or subambient temperatures where it is desirable to quickly close off a bottom discharge line or pipe to prevent escape of stored liquid.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. In combination:

a first valve closure and a first valve seat therefor,

a tubular guide extending vertically from the first valve closure,

a rod extending vertically from the first valve seat into the tubular guide,

a suspending means extending upwardly from the tubular guide and including an eccentric lever arm,

an orifice in the first valve closure,

a second valve closure capable of sealing the orifice,

and

a connecting member extending from the second valve closure to the eccentric arm,

whereby lifting the suspending means causes first the eccentric arm and connecting member to lift the second valve closure from a sealing position about the orifice and to then lift the first valve closure from a sealing contact with the first valve seat.

2. A combination according to claim 1 in which the orifice in the first valve closure has a central guide hole defined by a ring supported in the orifice and the second valve closure has a guide rod extending through the ring.

3. A combination according to claim 2 in which the guide rod extending through the ring has spring means below the ring which urges the second valve closure into sealing position over the orifice except when the connecting member from the second valve closure to the eccentric arm is raised.

4. A combination according to claim 1 in which the second valve closure has means to guide it into sealing arrangement with the orifice when the suspending means is in relaxed condition.

5. A combination according to claim 1 including a control means operably connected to the suspending means, said control means being capable when activated to raise and hold the suspending means in raised position with the valve closure above the valve seat and the valve thus open, and when deactivated to permit the suspending means to drop and the valve closure to automatically contact the valve seat and close the bottom opening.

6. A combination according to claim 5 in which the control means is pneumatically operated.

7. In an enclosed storage tank, for a liquid product, having a bottom opening communicating with a discharge pipe, and a fixed-position roof, the improvement comprising:

a fail-safe apparatus for closing the bottom opening internally of the tank, said apparatus including a valve means inside of the tank,

the valve means having a valve seat around the bottom opening and a valve closure adapted to span the bottom opening and contact the valve seat in closing the opening,

suspending means extending from the valve closure to a control means,

said control means being capable when activated to eccentric arm and connecting member to lift the second valve closure from a sealing position about the orifice and to then lift the valve closure from sealing contact with the valve seat.

8. The improvement of claim 7 including:

a rod on the second valve closure, and

means to guide the rod through the orifice in the valve closure.

9. The improvement of claim 8 in which the rod has spring means to urge the second valve closure into sealing position over the orifice except when the connecting member from the second valve closure to the eccentric arm is raised. 

1. In combination: a first valve closure and a first valve seat therefor, a tubular guide extending vertically from the first valve closure, a rod extending vertically from the first valve seat into the tubular guide, a suspending means extending upwardly from the tubular guide and including an eccentric lever arm, an orifice in the first valve closure, a second valve closure capable of sealing the orifice, and a connecting member extending from the second valve closure to the eccentric arm, whereby lifting the suspending means causes first the eccentric arm and connecting member to lift the second valve closure from a sealing position about the orifice and to then lift the first valve closure from a sealing contact with the first valve seat.
 2. A combination according to claim 1 in which the orifice in the first valve closure has a central guide hole defined by a ring supported in the orifice and the second valve closure has a guide rod extending through the ring.
 3. A combination according to claim 2 in which the guide rod extending through the ring has spring means below the ring which urges the second valve closure into sealing position over the orifice except when the connecting member from the second valve closure to the eccentric arm is raised.
 4. A combination according to claim 1 in which the second valve closure has means to guide it into sealing arrangement with the orifice when the suspending means is in relaxed condition.
 5. A combination according to claim 1 including a control means operably connected to the suspending means, said control means being capable when activated to raise and hold the suspending means in raised position with the valve closure above the valve seat and the valve thus open, and when deactivated to permit the suspending means to drop and the valve closure to automatically contact the valve seat and close the bottom opening.
 6. A combination according to claim 5 in which the control means is pneumatically operated.
 7. In an enclosed storage tank, for a liquid product, having a bottom opening communicating with a discharge pipe, and a fixed-position roof, the improvement comprising: a fail-safe apparatus for closing the bottom opening internally of the tank, said apparatus including a valve means inside of the tank, the valve means having a valve seat around the bottom opening and a valve closure adapted to span the bottom opening and contact the valve seat in closing the opening, suspending means extending from the valve closure to a control means, said control means being capable when activated to raise and hold the suspending means in raised position with the valve closure above the valve seat and the valve thus open, and when deactivated to permit the suspending means to drop and the valve closure to automatically contact the valve seat and close the bottom opening, an orifice in the valve closure, a second valve closure capable of sealing the orifice, and a connecting member extending from the second valve closure to an eccentric arm in the suspending means, whereby lifting the suspending means causes first the eccentric arm and connecting member to lift the second valve closure from a sealing position about the orifice and to then lift the valve closure from sealing contact with the valve seat.
 8. The improvement of claim 7 including: a rod on the second valve closure, and means to guide the rod through the orifice in the valve closure.
 9. The improvement of claim 8 in which the rod has spring means to urge the second valve closure into sealing position over the orifice except when the connecting member from the second valve closure to the eccentric arm is raised. 